Field of the Invention
The present invention relates to the technical field of magnetic resonance imaging, and in particular to a resonance imaging method regarding the carotid artery.
Description of the Prior Art
In magnetic resonance imaging of the carotid artery, magnetic resonance black blood imaging is becoming a powerful tool for carotid atherosclerosis research. In carotid artery magnetic resonance black blood imaging, pre-processing of carotid artery magnetic resonance imaging can be performed by applying methods such as double inversion recovery (DIR) or flow sensitive dephasing (FSD), etc. However, a problem of current magnetic resonance black blood imaging is that the scanning time is somewhat long, so that swallowing or other laryngeal movements are likely to occur during the process of acquiring data, causing unclear images (artifacts) as a result. Besides magnetic resonance black blood imaging, other imaging methods also have the problem of being affected by local movements so that the final image is unclear.
Specifically, swallowing can hardly be avoided during the process of carotid artery vessel wall imaging due to the long duration of scanning. FIG. 1 is a schematic diagram of a navigation sequence and an imaging sequence in the prior art, wherein the arc is a curve representing the magnitude of local movements.
As shown in FIG. 1, as regards the navigation sequence, firstly it is required to manually locate the position of a local movement, then a navigation pulse scanning is used regarding the position, thus detecting whether the local movement of the object under detection has entered an acceptance window, i.e. the window in which the magnitude and range of the local movement will not result in a huge effect on image sequence scanning, and only in the case that the local movement has fallen into the acceptance window, is imaging sequence scanning performed.
A three-dimensional turbo spin-echo (SPACE) sequence is a typical scanning mode in three-dimensional magnetic resonance black blood imaging. FIG. 2 is a time sequence schematic diagram of a three-dimensional turbo spin-echo sequence in the prior art. As shown in FIG. 2, in the three-dimensional turbo spin-echo sequence, firstly a 90° excitation radio frequency pulse is applied to a radio frequency (RF) signal, then a 180° rephasing radio frequency pulse is applied after the 90° excitation radio frequency pulse, then subsequent other radio frequency pulses are applied; and in the direction of slice-select gradient Gs, phase encoding gradient Gp and readout gradient Gr, a corresponding slice-select gradient, phase encoding gradient and readout gradient are respectively applied. During the process of scanning, an analog-digital converter (ADC) collects a signal, wherein the analog-digital converter (ADC) collects echo signals in the data acquisition timeslots (ACST) represented by dash areas.
The effect of local movements on the final image can be reduced by the aforementioned measures, but such a navigation sequence module will undoubtedly increase the complexity of the system and waste much time, especially in the case that local movements randomly happen and the probability of occurrence is relatively low, the necessity of using such a module is lower.
The above-described current solution has the following aspects to be improved regarding local movements: the system is relatively complicated, and it is required to add an additional navigation sequence module; the operation is relatively complicated, and it is required to manually locate local movements; it is relatively time-wasting; and the navigation pulse will generate black belt artifacts on the final imaging and affect the imaging quality.